Tensioning apparatus for pliable material



Jan. 8, 1963 P. l.` CRUZ 3,072,360

4 TENSIONING APPARATUS FOR PLIABLE MATERIAL Filed May 24, 1961 4Sheets-Sheet 1 INVENTOR.' PAUL L. CRUZ ATTORNEYS Jan. 8, 1963 P. L` CRUZFiled May 24, 1961 4 Sheets-Sheet 2 DRNEN 1HE-UP [fj- '98 Co'gkomm NanouTRANSMWTER PQE-asume- 5E) REGuLAToR'1'99 55 52. l |5402 IOO \-I AcTuAToRFILTER f2() W4 F- ouace- Z4 T56' 100V' Paesauae f5 SQUECE Q INVENTOR:

P 2 27 28. 1 AUL L. CRUZ ATTORNEYS Jan. 8, 1963" P. L. cRuz Filed May24, 1961 Kiwi TENSIONING APPARATUS FOR PLIABLE MATERIAL 4 Sheets-Sheet 3254 bau/EN "ml TMEUP INVENTOR:

PAUL L. CRUZ F 15T-15 "ByanwAlMfd/mgk ATTORNEYS Jan; 8, 1963 P. L.' cRuz.3,072,360

TENSIONING APPARATUS FOP. PLIABLE MATERIAL Filed May 24, 1961I 4Sheets-Sheet 4 MLM. L. CRUZ @MMHW ATTORNEYS Y 7: F INVENTOR:

United States Patent 3,072,360 TENSIONING APPARATUS FOR PLIABLE MATERIALPaul L. Cruz, Charlotte, N.C., assgnor, by mesne assignments, to RonsonCorporation, Woodbridge, NJ., a corporation of New Jersey Filed May 24,1961, Ser. No. 112,469 19 Claims. (Cl. 242-154) This invention relatesto apparatus for inducing and maintaining uniform tension in anindefinite length of strand, web or other pliable material, such astextile or metal strands, ropes, belts, fabrics, paper or plasticsheets, and the like.

It is a primary object of this invention to provide a tensioningapparatus capable of use with a wide range of sizes, shapes and weightsof different pliable materials and capable of inducing and maintainingconstant any of a Wide range of different tensions in such pliablematerials.

It is another object of this linvention to provide an apparatus formaintaining tension in a moving pliable material of indefinite lengthcomprising at least one rst element and atleast two spaced secondelements stradling said first element, said first and second elementsbeing engageable with opposite sides of the material to inducetortuosity in and apply friction to the material, and wherein actuatormeans is provided for varying the relative positions of said first andsecond elements independently of the tension in that portion of thematerial moving between said elements and thus serving to vary thetortuosity in and the friction applied to the material. A yieldablesensing element is spaced from said rst and second elements andengageable by and biased by the material after it passes said first andsecond elements, and the sensing element is responsive to the tension inthe l material after it passes said first and second elements to causesaid actuator means to vary the relative positions of said first andsecond elements whereby the tortuosity and friction induced in thematerial is Varied in accordance with variations in the tension of thematerial leaving the first and second elements to maintain uniformtension in the material, without relying on the pressure of the materialagainst the first and second elements for controlling the positionthereof.

It is another more specific object of this invention to provide atensioning apparatus including a device for applying frictionalresistance to the movement of said material therethrough, which deviceincludes means engaging substantially opposite sides of the material andcausing the material to move in a tortuous path, withfluid-pressure-operated means operatively connected to the engagingmeans for varying the tortuosity of the material to vary proportionallythe frictional resistance applied to the material. A movable sensingelement is yieldably biased against the material after it passes saiddevice, with means responsive to movement of said sensing devicerelative to an optimum position, at which optimum tension exists in thematerial, for varying fluid pressure in the fluidpressure-operated meansto an extent proportional to the movement of the sensing device tocorrespondingly vary the tortuosity of the material as it passes throughsaid device and thereby vary the frictional drag or resistance tomovement of the material therethrough.

It is another object of this invention to provide tensioning apparatusof the character described including means for applying a predeterminedcontrol point pressure to the fluid-pressure-operated means such thatthe sensing means must be biased a predetermined amount by the tensionin the material in order to be in equilibrium with the frictionalresistance applied thereto by the device so that said sensing devicevaries the pressure in the fluid 3,072,360 Patented Jan. 8, 1963 ICCoperated means relative to said control pressure with variation in thetension of the material above. and below a predetermined optimumtension.

It is still another object of this invention to provide a tensioningapparatus of the character last described wherein means are provided foradjusing the control point pressure Vto thereby effect yany of a widerange of optimum tensions in the moving pliable material.

Some of the objects of the invention having been stated, other objectswill appear as the description proceeds, when taken in connection withthe accompanying drawings, in which- FIGURE 1 is a top plan view of apreferred embodiment of the improved tensioning apparatus;

FIGURE 2 is a side elevation of the apparatus of FIGURE l with portionsof the base thereof broken away;

`FIGURE 3 is a rear elevation looking at the left-hand side of FIGURES land 2, with the base being shown in cross-section;

FIGURE 4 is a front or egress end elevation of the apparatus looking atthe right-hand side of FIGURES 1 and 2;

FIGURE 5 is a schematic diagram of the preferred embodiment of theapparatus;

FIGURE 6 is a longitudinal sectional view taken substantially along line6-6 in FIGURE l and showing a motion transmitter which convertsmechanical movement of the sensing element into direct linear fluidpressure;

FIGURE 7 is an enlarged fragmentary View of the left-hand portion ofFIGURE 6;

FIGURE 8 is a longitudinal vertical sectional view through an actuatoror positioner for the friction applying device, and being takensubstantially along line 8 8 in FIGURE 4;

FIGURE 9 is an enlarged fragmentary view of the upper portion of FIGURE8;

FIGURE 10 is an enlarged somewhat schematic vertical and longitudinalsectional view through a controller for comparing a predeterminedcontrol point pressure with linear variations in pilot pressure effectedby the motion transmitter for controlling the actuator in Iaccordancetherewith, and being taken substantially along line S10-10 in FIGURE 3;

FIGURE 1l is a fragmentary vertical sectional View taken along line11--11 in FIGURE 2;

FIGURE 12 is a fragmentary Vertical sectional view taken substantiallyalong line 12-12 in FIGURE 2;

FIGURE 13 is a partially schematic view similar to the upper right-handportion of FIGURE 5 and showing a second embodiment of the tensionsensing device in association with the motion transmitter.

General Synopsis of the Invention The present embodiment of theinvention is shown as being particularly arranged for applying andmaintaining uniform tension in a moving pliable element of indefinitelength, which pliable element is shown in the form of a strand S drawnfrom a suitable source Ztl by a suitable driven take-up mechanism 21(FIGURE 5), with the friction applying device 22 and one embodiment ofthe sensing or detecting device 23 being serially arranged betweensource 20 and take-up mechanism 21. Itis to be distinctly understoodthat the principles of the present invention may be readily adapted forapplying and maintaining uniform tension in any type of pliable materialof indefinite length in web or strand form.

The strand of pliable material S passes from source 20 successivelypartially around a pair of flanged guide pins or rollers 24, 25 to thefriction applying device 22. Friction applying device 22 includes meanscontacting and producing a variable tortuous configuration in the strandS passing therethrough and comprises a plurality of spaced,substantially parallel fixed pins or shafts 26, 27, 2S, which arepreferably fixed against rotation as well as being fixed with respect tothe base or frame 30 of the tensioning apparatus.

A pair of laterally or vertically movable, preferably non-rotatable pins32, 33 are provided which are so positioned as to be moved inwardly andoutwardly or downwardly and upwardly in spaced intermeshing relation toand between the fixed pins 26, 27 and 27, 2.8. Strand S passes betweenthe upper and lower friction including pins 32, 33 and 26-28, fromwhence it passes partially around a roller 34. The pins 26-28, 32, 33,which may also be termed as friction applying elements, should havesmooth arcuate surfaces engaging strand S and preferably the pins arecircular in cross-section.

Roller 34 is offset forwardly with respect to a sensing element orroller 36 so as to form a loop in the strand S as it passes rearwardlyfrom roller 34 and then substantially half-way around sensing roller 36,from whence the pliable material S passes forwardly to the takeupmechanism 21. Sensing roller 36 is journalled, on a shaft 37 fixed onthe free end of a yieldable member, the first embodiment of which isshown inthe form of a cantilever 40 suitably secured to a bracket 41fixed to the base 30.

It will be observed in FIGURES 2, 4, and 6 that the shaft 37, on whichsensing roller 36 is mounted, is engaged by a follower 42 having a stemor shaft 43 extending therefrom. Follower 42 is a part of a motiontransmitter broadly designated at 44 and may be pivotally or otherwisedirectly connected to the shaft 37 or the cantilever 40. It ispreferred, however, that follower 42 is lightly urged into engagementwith the rear surface of shaft 37, as by a compression spring 45, oneend of which bears against follower 42 and the other end of which bearsagainst the rear end of the housing 46 of motion transmitter 44. Themotion transmitter may be of a type disclosed on opposite sides of aBulletin 1102A, copyrighted 1956, by Moore Products Co., H and LycomingStreets, Philadelphia, Pennsylvania, for example.

Stem 43 is guided for longitudinal movement in a bearing 47 carried byhousing 46 and has a longitudinally adjustable extension 50 on its innerend whose end opposite from stem 43 has a pilot valve 51 thereon whichserves as a bleed-off valve. By means to be later described, pilot valve51 is instrumental in converting any longitudinal mechanical movement offollower 42 into a given range of pilot air pressures, preferably offrom 3 to l5 pounds per square inch gauge pressure. The range ofpressure transmitted by motion transmitter 44 is in direct linearrelationship with the range of movement of pilot valve 51 as effected bymovement of the sensing roller 36.

The measured variable pilot pressure is transmitted from motiontransmitter 44, through a pipe or conduit 52, to a controller broadlydesignated at 53. The controller 53 is a form of pressure relay into aportion of which a predetermined control point pressure is introducedand into another portion of which the variable pilot pressure from themotion transmitter is introduced. These pressures are compared toproduce a signal pressure at the output of the controller 53.

The controller 53 operates in such a manner that, when pilot pressure isincreased due to outward movement of the valve stem 43 in the motiontransmitter of FIGURE 6, this increases the output signal pressure ofthe controller and, when the pilot pressure is decreased due to inwardor right to left movement of the valve stem 43 in the motiontransmitter, pressure escapes from the controller and is thus reduced atthe output of the controller. The controller 53 may be of a type knownas a Nullmatic Controller-Model 55 disclosed in an instruction book No.SD 50-3, copyrighted 1958, by said Moore Products Company, for example.

The output side of controller 53 is connected to a control unit 183 ofan actuator, broadly designated at 54, by a pipe or conduit 55. Actuator54 is a form of air motor including a double-acting cylinder or housing56 within which a piston 57 is positioned, and which piston has a pistonrod or plunger 60 extending downwarly therefrom in FIGURES 2, 3, 4, 5and 8. The cylinder 56 and piston 57 may be termed as relatively movableparts of actuator 54. The piston rod 60 has a bracket 61 adjustablysecured on the lower end thereof. Bracket 61 has a pair of dependingarms 62 thereon on which the vertically movable friction inducing orpressure pins 32, 33 are xedly mounted. The actuator 54 may be of a typedisclosed on pages 4 and 5 of a catalogue entitled Annin ActuatorBulletin No. 1236ST, published by The Annin Company, 1040 South VailAvenue, Montebello, California, for eX- ample.

The signal pressure transmitted to the actuator 54 from controller 53controls the introduction and exhaust of compressed air from the mainline into the cylinder 56 below the piston 57 in such a manner that anyincrease in the signal pressure transmitted from the controller 53introduces high air pressure into cylinder 56 below piston S7 to causepiston 57 to move upwardly a distance determined by the signal pressurein pipe 55 and, upon any decrease in the pressure in pipe 55, air isexhausted from the lower end of cylinder 56 as high main line airpressure is effective above piston 57 to move piston 57 and piston rod60 downwardly until the pressure exerted on a control element of thecylinder 56 is in equilibrium with the force exerted by the signalpressure from the output side of controller 53.

The control point pressure in controller 53 is pre-set such that thepull of strand S against sensing roller 36 must exert a predeterminedamount of force such as to place the cantilever 40 under straincorresponding to the amount of tension to be maintained in the strand Swhen the entire fluid circuit is in equilibrium. When the entire fluidpressure circuit is in equilbrum, the movable friction applying pins 32,33 occupy a predetermined intermeshing relationship with respect to thexed pins 26-28 such as to maintain a frictional resistance to movementof the strand S through the friction applying device 22 which is inequilibrium with the amount of strain placed upon the cantilever 4t) bythe pull of the strand S against the sensing element 36.

Thus, upon any tendency for the tension in the strand S to be relaxed,such as to permit the sensing roller 36 to move rearwardly or from rightto left in FIGURES l, 5 and 6, the consequent inward or right to leftmovement of pilot valve 5l of FIGURE 6 produces a corresponding changeor reduction in pilot pressure transmitted from the motion transmitter44 through conduit 52 to controller 53. Thereupon, the controllercompares the difference between the pre-established control pressure andthe pilot pressure and correspondingly reduces the output signalpressure of controller 53. Consequently, the pressure in the controlunit E83 of the cylinder 56 of actuator S4 is also reduced to exhaustair from the bottom of cylinder 56 as high main air pressure enterscylinder 56 above piston 57. This causes piston 57, piston rod 6i) andmovable friction applying pins 32, 33 to move downwardly in furtherintermeshing relationship to the xed pins 26-28, thus increasing thefrictional resistance to movement of the strand S through the frictionapplying device 22 to an extent such as to cause the sensing roller 36to return to its optimum position due to the increased tension impartedto the strand S moving in engagement therewith.

Conversely, if the tension in strand S tends to become higher than thedesired optimum tension, the vertically movable pins 32, 33 of frictionapplying device 22 move upwardly, because the stem 43 in transmitter 44moves to the right with roller 36 and increases the pilot pressuretransmitted from transmitter 44 to controller 53. Here again, the pilotpressure is automatically compared with in conduits 100, 102, whichpressure is preferably reduced to approximately 20 pounds per squareinch gauge at the pressure regulator 99, this being a regulated supplypressure for the motion transmitter 44 and controller 53 which exceedsthe maximum pilot pressure and signal pressure to be transmitted by themotion transmitter 44 and the controller 53.

Controller As heretofore stated, controller 53 (FGURES l-5 and l) is afor-m of relay which receives measured vvariable pilot pressurestransmitted thereto through conduit 52 from motion transmitter 44 andthese measured variable pilot pressures are compared with a pre-setcontrol point pressure in the controller. The control point pressure isestablished so the movable friction applying pins 32, 33 and the plunger60 and piston 57 of actuator 54 occupy pre-established positionsrelative to the fixed pins 26-28 when sensing roller 36 is biased to apredetermined position by the pull of the moving strand S thereagainstand the force of the pilot pressure is in balance with the control pointpressure in controller 54. However, when there is any Variation in thepilot pressure, due to lluctuations of the sensing roller eifected bytendencies of the tension to vary in the strand S, such pilot pressurevariations are compared with the control point pressure to effectcorresponding changes in the signal pressure transmitted from thecontroller 53 to the control unit of the actuator 54.

The controller 53 includes a housing 107 of built-up construction whichincludes a control point setting regulator 110, a reset unit 1111, athrottling unit 112 and a signal pressure unit 113. The housing 107includes chambers 114423. Chamber i114 is located in the control pointsetting regulator 110 and is vented to the atmosphere, as at 130. Amanual adjustment screW 131, having a control knob 132 on its upper end,is threaded through the upper end of housing 107 and has a hanged springseat 133 journaled on its lower end within chamber 1i1i4 and againstwhich the upper end of a compression spring 1-34 is positioned.

The other or lower end of compression spring 134 bears against abuilt-up regulator base 135 which serves as a reinforcement for thecentral portion of a flexible diaphragm 1316 mounted in housing 107 andserving to separate chambers 114, 115. The central portion of regulatorbase 135 bears against a nozzle seat plate 137 spaced above thecorresponding portion of a lateral partition 140 Iwhich serves toseparate chambers 115, 116.

A reduced lower portion of chamber 115 has a nozzle itherein whichcommunicates with the atrnospehre through a vent or port 141 formed inpartition 140. The restricted upper end of nozzle i is adapted to beclosed and opened by a throttling valve or nozzle seat k iixed to orformed integral with and depending from the central portion of nozzleseat plate 137. One side wall portion of housing 107 has alongitudinally extending passageway 142 therein which extends alongpartition .140 and communicates with chamber 115, at one end thereof.The other end of passageway 1412 communicates with chamber 1213.

The end of conduit 98 opposite from pressure regulator 99 is connectedto housing 107 for communication with chamber 123. Thus, regulatedsupply pressure is admitted into chamber 123` and passageway 142.However, partition 140 has a reducing valve 143 therein which isinterposed in passageway 142 so that the pressure admitted into chamber115 may be substantially less 4than the regulated pressure admitted intochamber 123. Spring 134 in the control point regulator 110 is adjustedso as to constantly maintain a predetermined pressure in chamber 1'15,it being apparent that, when the pressure in chamber 115 exceeds theoptimum desired control point pressure, diaphragm 136 and regulator base135' move upwardly in FIGURE ll and, since pressure is introduced intochamber 115 through passageway 142 at a point beneath the nozzle seatplate 137, nozzle seat plate 137 also moves upwardly, raising throttlingvalve k out of enagement with nozzle i and permitting pressure to escapefrom chamber through port 141.

Conversely, when the control point pressure in the chamber 1115 isreduced below optimum pressure, the pressure of spring 134 againstregulator base 135 is such that the regulator base 135 moves nozzle seatplate 13-7 and nozzle seat k into engagement with nozzle to permitadditional pressure to enter chamber 115 through passageway 142, thuscompleting the description of the control point setting regulator 110 ofcontroller 53.

The chambers 1116, 117 are separated by a transverse partition 144, andthe chambers 117-120 are defined by spaced flexible diaphragms 145, 146,147 which are interconnected by a built-up valve core'm. It should benoted that the housing l107 is so constructed that the opposed sides ofintermediate diaphragm 1146 have substantially less effective surfacearea than opposed sides of the diaphragms 145, 147.

A diaphragm 116e is positioned in chamber 116 closely above partition144. The space below diaphragm 116e is open to the atmosphere by a smallpassageway 116b in partition 144. Chamber 1.15 is in continuouscommunication with control point chamber '118 between the diaphragms146, by means of a conduit 150, to which conduit a suitable controlpoint pressure indicating gauge 151 may be suitably connected. -A pairof reducing valves 116C, 116d in partition 144 provides communicationbetween passageway 142 and the bottom of chamber 116 and betweenchambers 116, 117, respectively.

The chambers 120, 121 are separated by a partition 1512 having a nozzle153 therein, whose restricted upper portion is positioned within areduced lower portion of chamber 120, and which establishescommunication between chambers 120, 121 whenever the lower end of valvecore m is out of sealing engagement with nozzle 1153 due to the controlpoint pressure in chambers 115, 118 being greater than the pilotpressure in chamber 119. It should be noted that conduit 5=2 isconnected to housing 107 for communication with chamber 119.

When the pilot pressure in chamber 119 tends to exceed control pointpressure in chamber 118, diaphragms 145, 146, 147 and valve core m movedownwardly to close the nozzle 153. Chambers 120, `122 are in continuousintercommunication through the medium of a passageway 155 formed in oneside wall portion of housing 107.

A passageway n in partition 144 establishes continuous communicationbetween chamber 117 and passageway 155, although a restricting valve pis shown interposed in the passageway n, which valve is manuallycontrolled by a knob 156. Passageway 155 also communicates with chamber116 through the medium of a manually operated restricting valve q Iwhichis controlled by a knob 157. However, since the chamber 116, diaphragm116a and valves p, q are provided primarily for the purpose of delayingthe action of diaphragms 145, 146, 147 in response to any sudden changesin the relative pressures in chambers 118, 119 and 120, which is notentirely necessary in the present embodiment of the invention, adetailed description of the function of valves p, q, diaphragm 116evalves'116c, 11611 is deemed unnecessary. To all intents and purposes,it is suicient to state that the pressure in all the chambers 117, 120and -122 and in passageway 155I is the same and is actuallysubstantially equal to the signal pressure transmitted from chamber 122to the control unit of actuator 54. It should be noted that conduit 55is connected to housing 107 o controller 53 for communication withchamber 122. The signal pressure in chambers 120, 122 is varied relativeto the control point pressure in direct relation to the pilot pressurein chamber 119.

The chambers 121, 122 are separated by a pair of closely spaced exiblediaphragms r, s defining an exhaust chamber ttherebe'twecn which is opento the atmosphere.

the pre-established control point pressure in controller 53 so thatpressure is released from the output area of controller 53 and thusreleased from the control unit of actuator 54.

When pressure is released from the control unit of actuator 54,additional pressure enters cylinder 56 of actuator 54 below piston 57 tomove piston 57, piston rod 60 and movable friction applying pins 32, 33upwardly until the force exerted against the control unit 183 ofactuator 54 is again in equilibrium with the force exerted by the signalpressure in the output side of controller 53, in conduit 55 and in thecontrol unit 183 of actuator 54.

It is apparent that only very slight uctuations of the sensing roller 36may occur during travel of the strand or other pliable material throughthe tensioning apparatus and that, even though these lluctuations arecaused by tendencies for the strand S to become slackened orovertensioned, the biased cantilever 40 still maintains constant anduniform the tension in the strand S. This is due to the fact that theslightest movement of pilot valve 51 converts the linear mechanicalmovement of the follower 42 to a linear pressure change which isinstantly compared with the control pressure and produces aninstantaneous change in signal pressure in the control unit of actuator54. This causes the movable pins 32, 33 of friction applying device 22to move in such direction as to rectify any changes in the tension ofthe strand S and causes the sensing roller 36 to return to its optimumposition under the pull of the loop formed of the strand S passing aboutthe sensing element or roller 36.

It should be noted that the actuator 54 changes the position of pins 32,33 with changes in signal pressure, but the pressure of pins 32, 33against strand S may or may not be changed, since the pins 32, 33 simplyvary the tortuosity of the strand to vary the angle of contact of thestrand against pins 26-28, 32, 33 with consequent variation in thefriction applied to the strand. Any increase or decrease in the pressureof pins 32, 33 against strand S is incidental and would generally occurduring actual movement of pins 32, 33 relative to pins 26-28.

Motion Transmitter The housing 46 of motion transmitter 44 is suitablysecured to the base 30 rearwardly of the cantilever 40 and sensingroller 36, as will be later described.

The housing 46 of motion transmitter 44 is of hollow construction and isprovided with a series of chambers 65-71 therein (FIGURES 6 and 7). Thechamber 66 is open to the atmosphere by means of a vent or port '75provided in the wall of chamber 66. The wall of chamber 69 also has avent 76 open to the atmosphere. The chambers 65, 66 are separated by arestriction 77 in the wall of housing 46 and in which a tubularadjustment screw 80 is threadedly mounted.

Chambers 66, 67 are separated by a partition 81 and chambers 67, 68 areseparated by a partition 82. Chambers 68, 69 are separated by a flexiblediaphragm 83 having a movable valve seat member 84 mounted in thecentral portion thereof` Chambers 69, 70 are separated by a partition 85(FIGURE 7) through which valve seat member 84 loosely extends and whichhas a ilexible diaphragm a connected thereto.

The left-hand portion of valve seat member 84 is connected to diaphragma so the diaphragms 83 and a move in fixed relationship to each other,The valve seat member 84 is provided with a passageway b which providescommunication between chambers 69, 70 when a needle valve c is out ofengagement with valve seat member 84 for exhausting air from chambers 67and 70 to the atmosphere through vent 76, it being noted that chambers67 and 70 are connected by a passageway 86 so the pressure in bothchambers 617, 70 is equal at all times. Needle valve c loosely extendsthrough a partition 87 which separates chambers 70, 71.

A medial portion of needle valve c has a ball valve d thereon which isnormally yieldably urged or springpressed against a valve seat formed bya port or passageway e through partition 87. A compression spring f ispositioned between valve seat member 84 and partition 87 and tends tourge member 84 away from needle valve c. The conduit 52 is connected tohousing 46 of motion transmitter for communication with chamber 70, anda pipe or conduit 90 is connected to housing 46 for communication withair supply chamber 71. Conduit 90 is connected to a regulated supplypressure source, as will be later described, so that a pressure inexcess of the maximum pressure transmitted by the motion transmitter isalways present in supply chamber 71.

The portion of the wall of housing 46 of motion transmitter 44 adjacentcompartments 67, 68, 70 has a passageway 91 therein which also extendsinwardly within partition 81 and communicates with the interior of apair of interconnected bellows 92, 93 disposed in the respectivechambers 66, 67. The bellows 92, 93 are interconnected by a rigid coremember 94. Core member 94 loosely extends through partition 81 andilanged opposite ends thereof are connected to the distal ends ofbellows 92, 93.

The core member 94 has a chamber g therein which communicates withbellows 92, 93 and within which the pilot valve 51 is loosely positionedto serve as a bleedot valve. The outer or right-hand end of chamber g isrestricted, as at g', and the adjacent end portion of the stem extension50 is of reduced diameter relative to the diameter of pilot valve 51 sothat movement of pilot valve 51 from left to right in FIGURE 6 furtherrestricts and prevents the flow of air outwardly through restriction g.Of course, inward or right to left movement of pilot valve 51 opensrestrtiction g so that a greater amount of air may pass outwardlytherethrough and be bled to the atmosphere through the port 75 in thewall of housing 46.

It will be noted that passageway 91 also communicates with chamber 68and supply chamber 71. However, the end of passageway 91 adjacent supplychamber 71 is provided with a throttling valve h so the pressureadmitted into chamber 68 and bellow 92, 93 may be substantially lessthan the pressure admitted into supply chamber 71. Also, the pressure inchamber 68 and bellows 92, 93 is substantially less than the pressure inchambers 67, 70. It should be noted that passageway 91 is actuallyclosed with respect to discharge port 76, and is shown extending throughdischarge port 76 only for purposes of clarity.

The core 94 within bellows 92, 93 is yieldably urged to the left inFIGURE 6, under relatively light pressure, by a compression spring 95,one end of which bears against the flanged right-hand or outer end ofcore 94, and the other end of which bears against a tubular spring seator guide 96 which is keyed, as at 97, in the restriction 77 and isadjusted inwardly and outwardly by the adjustment screw 80.

As heretofore stated, a regulated pressure is introduced into the supplychamber 71 of motion transmitter 44. To this end, it will be observed inFIGURE 5, in particular, that conduit 90 is connected to a conduit 98,one end of which is connected to the controller 53 and the other end ofwhich is connected to a manually operable pressure regulator valve 99which serves to reduce the pressure transmitted to the controller 53 andthe motion transmitter 44 from a main or high pressure pipe line orconduit 100 leading from a suitable source of compressed air or iluidpressure P.

A suitable lter F may be inteposed in conduit 100 for removing anyimpurities or moisture from the air before its passage through pressureregulator 99. Also, a high pressure air line pipe or conduit 102 isconnected to conduit 99 at a point lbetween pressure regulator valve 99and tilter F, the other end of conduit 102 being connected to theactuator 54 in a manner to be later described.

The pressure source P preferably produces air pressure of approximately100 pounds per square inch gauge A suitable yieldable and; porousmember, suchas a wire screen u, maintains diaphragms'. r, s in spacedrelationship sothese two diaphragms move in fixed relationship to eachother. A flanged Valve seat v penetrates and is suitably secured to thebottom diaphragms s, this valve seat being engageable and closable by Vaneedle Valve w which extends through a passageway x formed in apartition 160 separating chambers 122, 123.

The lower end of passageway x serves as a seat for a ball valve y formedintregal with or secured to the stem of needle valve w. 'Ball valve y isnormally urged to closed position by a relatively small, lightcompression spring z positioned in chamber 123. A passageway 161 isprovided in partition 152 for establishing communication betweenpassageway 142 yand chamber 121. A suitable throttling or restrictingvalve 162` is positioned in passageway '1611 so the pressure ofthe airinchamber 121 may be substantially less than the pressure in passageway142. The operation of the controller 53 will be later described inconjunction with the operation of the actuator 54.

Actuator or Positioner The actuator (FIGURES 1-5, 8 and 9) operates onthe principle of application of a substantially constant high pressureto a small surface area at one side of a piston of a double-actingcylinder and application of a variable pressure against a substantiallylarger suriace area at the other side of the piston, causing the pistonto move in response to controlled variations in the amount of pressureapplied against the larger surface area of the piston in opposition tothe constant pressure applied to the relatively small area side of thepiston.

As best shown in FIGURE 8, piston 57 of actuator 54 has a tubularportion 170, of lesser diameter than the piston S7, projecting upwardlytherefrom and which moves in sealing engagement with a restriction 172formed in a medial portion of cylinder 56, thus providing an annularchamber 173 above piston 57 into which pressure from the main linesource P is constantly admitted through the medium of a conduit 174. Aresilient annular seal 175 may be provided between tubular portion 170and restriction 172; -One end of a conduit 174 is connected to conduit102 and the other end is connected to cylinder 56 for 'communicationwith chamber 173.

Since the tubular portion 170 of piston 57 is in sealing engagement withvthe restriction 172, it is apparent tha-t the pressure in chamber 173is effective upon a relatively `small surface area of piston 57 ascompared to the surace area of piston 57 which is exposed opposite fromthe tubular portion 170 thereof. The restriction 172 separates chamber-173 from a chamber 176 which is vented to the atmosphere, as at 177,and within which a compression spring 180 is positioned.

Plunger 60 is attached to piston 57, extends upwardly within tubularportion 170i and has a spring seat 181 adjustably mounted thereon, as bybeing threaded thereon. The lower end of spring 180 engages spring seat181. The upper end of the chamber 176 of cylinder 56 is closed by adiaphragm `182 which is a part oi actuator control unit broadlydesignated at 183 (FIGURES 8 and 9). Control unit 183 comprises ahousing 184, of built-up construction, which is suitably secured to theupper end of cylinder 56 and serves to `secure diaphragm 182 against theupper end of cylinder 56.

The housing 184 of control unit 183 is provided with a signal pressurechamber 185 and a venting chamber 186, the bottom of signal pressurechamber 185 being defined by diaphragm :182 and the top thereof vbeingdefined by a diaphragm 187 having lesser effective surface area thandiaphragm 182. Diaphragm 187 also separates chambers 185, 186.

The central portions of diaphragms 182, 187 are separated -by a spacingblock v190 of greater diameter at its lower portion than at its upperportion. Block 190 is of substantially lesser diameter than the openingat the upper end` of cylinder 5-6 and the chamber 186, respectively. Thediaphragms 182, 187 are suitably attached to respective upper and lowersurfaces of spacing block 190, as by a plate or spring seat 192 and aplate 193. The upper end of spring bears against spring seat 192. Areduced lower extension on a signal pilot valve 194, which serves asableed-oft` valve, engages the upper surface of plate 193. v Y

Signal pilot valve 194 is positioned in a relatively small valve chamber195v communicating with vent chamber 186 and defined at the juncture ofa pair of passageways 196, 197 formed in the housing 184 of control unit183. Conduit 102 is connected to control unit 183 for communication withpassageway 196. A conduit or pipe 200 has one end thereof connected tocontrol unit 183 for communication with passagewayl 197.

The other end of conduit 200 communicates with a chamber 201 defined inthe bottom portion of cylinder 56 by the lower surface of piston 57 anda cylinder closure member 202 through which piston rod 60 extends. Ventchamber 186, and thus valve 194 communicating therewith is bled orvented to the atmosphere through one or more passageways B which extendthrough the plates 192, 193 and through the spacer block 190 betweendiaphragms 182, 187. The operation of actuator 54 and its control unit183 will be later described.

Referring now to FIGURES l, 2, 3 and 4, it will be observed that theclosed lower end of cylinder 56 of actuator 54 is suitably secured tothe horizontal upper portion of an inverted substantially L-shapedbracket 205 whose 4substantially vertical portion is suitably secured toland projects upwardly Ifrom base 30. Piston rod 60 loosely penetratesthe horizontal upper portion of .bracket 205 :and is secured tot a bossportion 206 intergal with and projecting outwardly from bracket 61, sothe center of plunger 60 may be substantially alined with the center ofpin 27.

Controller 53 may be suitably secured in fixed relation tothe base 30 inany desired manner. In this instance, the upper end of housing 107 isxed to an angle bracket 210 suitably secured to an upright plate 2111which projects downwardly and is suitably secured to base 30.

The rollers 24, 25 may be journaled or xed on the upper ends of posts212, 213, whose lower ends are suitably secured to base 30. The osetroller 34 also may be xedly mounted or journaled upon the upper end of apost 214, whose lower end is suitably secured to base 30. ln order toinsure that the friction applying device 22 is effective to tension thepliable material S, particularly in instances in which relatively heavytension is to be applied -to the material S, it is desirable that thematerial S have some input ltension therein, although such input tensionmay vary considerably fan-d need not be controlled. Accordingly, rollers24, 25 are preferably fixed on the upper ends of the posts 212, 213.`Further, the rollers 24, -25 may -be so positioned relative to eachother that there is a greater langle of contact between material S androllers 24, 25 than that shown in FIG- URES l and 5, i-f desired, toincrease the input tension of the material S entering the frictionapplying device 22.

In instances in which a relatively Ilight output tension is to beapplied to the strand :as it leaves sensing device 23, it is apparentthat the weight of .the pliable material S may serve to inducesuflicient input tension therein so the rollers 24, 25 may then berotatably mounted on the posts 212, 213. Als-o, some input tension maybe induced in the material at the soucce, since the source may be in the-form of folds, layers or a roll of the pliable material, tor example.

It is apparent that the base 30l of the apparatus must be secured infixed rela-tion to the driven take-up mechani-sm 21. Each station-arypin 26, 27, 28 is fixed to and 1 1` projects outwardly from the uprightportion of a corresponding angle bracket 215 suitably secured to base 38(FIGURE 12). It will be observed in FIGURE 1l that each pin 32, 33 isxedly mounted on and extends outwardly from the bracket 61.

M ethOd of Operation As heretofore stated, the present tensioningapparatus may be used `for applying tension to many diierent types ofmoving pliable materials of indefinite length and, for purposes ofdescription, it is `to be assumed that a tow or rope of syntheticlilaments is to be drawn from a source at relatively little tension, sayfrom 1/2 to l pound tension, and is to have 15 pounds of tension apAplied thereto `as it is taken up by the driven take-up mechanism, suchas for the pur-pose of cutting the same into staple lengths, `forexample. It is to be further assumed that the pressure at pressuresource P, which pressure may be produced by a suitable compressor, isapproximately 100 pounds per square inch gauge and that pressureregulator 99 reduces this pressure to a regulated pressure ofapproximately 2O pounds per square inch gauge, this being the regulatedpressure introduced into the supply chamber 71 of motion transmitter 44-(FIGURE 6) and the supply chamber 123 of controller 53 (FIGURE l0)through the respective conduits 90, 98.

In this example, it may be assumed that the valve h of FIGURE 6 reducesthe pressure Afrom supply chamber 71 to 1.5 pounds per square inch gaugein .passageway 91, bellows 92, 93 and chamber 68, 'and that the pilotpressure in chambers 67, 70 of transmitter 44, pipe 52 and chamber 119of controller 53 may vary from 3 to l pounds per square inch gauge.

Assume further that the average tortuosity required in the moving strandS is obtained when the control point setting regulator is adjusted tomaintain a control point pressure of 10 pounds per square inch gauge inthe chambers 115, 118 of controller 53, and that the pressure in thecontroller chambers 117, 120 and 122, and consequently the pressure inchamber 18S of the control unit 183 of actuator 54 Imay Vary from 3 to15 pounds per square inch gauge.

Now, in order for lthe entire pressure system or circuit to be inequilibrium, it is apparent that the pressure in ,the chambers 67, 70 ofmotion transmitter 44, and chambers 1'18, 119 of controller 53 must beequal to the control point pressure of l() pounds per square inch gauge.Also, pressure in chambers 117, 120 and 122 of controller 53 and inchamber 185 of control unit 183 must be equal. Under equilibriumcondition, the pressure level in chambers 67, '70, 118, 119 may or maynot be equal to the pressure level in chamber 117, 120, 122 and 185,depending entirely upon the output tension inducing factors such asinput tension land/ or coefcient of friction between strand S and thepins 32, 33 and 26-28. Assuming that the free end of cantilever 40 isdeected .O26 inch when the movable pins 32, 33 occupy the position inwhich they are shown in FIGURE 2 and the coefficient of friction betweenthe pins 26-28 and 32, 33 and the str-and S combined with the totalangle of contact of the strand S with the pins is then such las toinduce pounds of tension in the moving strand S, this means that thepilot valve 51 is so positioned with respect to the restriction g' as topermit a predetermined amount of kair to escape from the bellows 92, 93through the restriction g' and outward-ly through port 75 (FIGURE 6)such that the pilot pressure in chamber 70 applies an amount of left toright force to the relatively small area of diaphragms a, along withspring f, equal to the opposing force exerted on the relatively largesurface area of diaphragm 83 by the pres-sure in chamber 68 so that thatis a balance of forces within the motion transmitter 44.

Upon any tendency for the tension in the strand S to increase, it isapparent that the deflection of cantilever 40 increases, permittingpilot valve 51 to move from left to right under the inuence of spring 45(FIGURE 6) and proportionally further restricting the outward iiow ofair from bellows 92, 93. Consequently, the pressure in chamber 68increases, moving diaphragms 83 and a from right to left in FIGURE 7 tomove valve seat 84 against needle valve c and close the same against theexhaust of air from chamber 70.

In so doing, valve seat 84 moves needle valve c and ball valve d fromright to left, permitting air to flow from supply chamber 71 intochambers 70, 67 to increase the pressure in the latter chambers fromsaid 10 pounds per square inch to, say, l1 pounds per square inch, forexample. As the pressure increases in chamber 67, this pressure causescore 94 and bellows 92, 93 to move from left to right to again reducethe pressure within the bellows and chamber 68 to balance the forces ofthe pressure in chambers 70 and 68 acting upon diaphragms a and 83 andreturn the motion transmitter to a state of equilibrium whiletransmitting a pilot pressure of 11 pounds per -square inch throughconduit 52 to the chamber 119 of controller 53 (FIGURE 10).

Since the pressure in chamber 119 is then greater than control pointpressure in chamber 118, and the pressures in chambers 117, 120 are eachequal to the other, diaphragms 145, 146, 147 and valve core m movedownwardly in FIGURE l0 to close nozzle 153 and thus increase thepressure in chamber 121 to such extent that the force applied againstthe upper surface of diaphragm r is greater than the opposing forceapplied against the diaphragm s by the signal pressure in chamber 122and spring D.

It is apparent, therefore, that the valve seat v moves moves downwardlyagainst needle valve w, moves ball valve y away from passageway x, andregulated air ows from supply chamber 98 through passageway x intochambers 122, 120 to increase the signal pressure in the latter chambersto, say, ll pounds per square inch.

The increased signal pressure is transmitted to the chamber (FIGURES 8and 9) between diaphragms 182, 187 in control unit 183 through themedium of pipe 55. With an increase in pressure in chamber 185, sincediaphragm 182 has a larger eifective surface area than diaphragm 187,the diaphragms 182, 187, spacer 190 and plates 192, 193 move downwardlyagainst spring 180. When plate 193 moves downwardly with the diaphragms182, 187, signal pilot valve 194 moves downwardly therewith andestablishes or increases communication between main air pipe 102 andpipe 200 through the medium of passageways 196, 197, thus increasing thepressure in chamber 201 beneath piston 57. This causes piston 57 to moveupwardly, raise movable pins 32, 33 therewith, and increase the pressureexerted on the diaphragms 182, 187 by spring 180.

When piston 57 and movable pins 32, 33 move upwardly sufliciently towhere the pressure of spring 180 exerts an upward force on thediaphragms 182, 187 which is equal to the force applied to the uppersurface of diaphragm 182 by the signal pressure in chamber 185, thediaphragme 182, 187 move upwardly, raising plate 193 and valve 194therewith and stopping the How of air from pipe 102 into pipe 200 andchamber 201. As heretofore stated, the piston 57 moves upwardly withincreased pressure in chamber 201 due to the relatively small area ofthe upper surface of piston 57 as compared to the lower surface thereof.The upward movement of piston 57 compresses the air in chamber 173 veryslightly and this compression is merely absorbed in the pipe 102, 100and pressure source P.

It is thus seen that the movable pins 32, 33 move upwardly or partiallyout of intermeshing relationship with xed pins 26-28 to reduce thetortuosity in strand S, thus reducing the resistance to movement of thestrand and the consequent tension in the strand so that the canti 13lever 40 and its sensing roller 36 return to the optimum position. y

Now, when the sensing roller 36 returns to said optimum position, theentire uid pressure circuit is returned to a state of equilibrium orsteady state condition, because the pilot valve 51 moves inwardly orfrom right to left in FIGURE 6 relative to restriction g to its originaloptimum position. The operation of the apparatus is then as follows:

`(l)V The exhaust of air from bellows 92, 93 increases.

(2) The pressure in bellows 92, 93 and chamber 68 of motion transmitterdecreases.

(3) The valve seat 84 moves further away from needle vlave c, permittingair to escape from chambers 67, 70 through port b, chamber 69 andexhaust port 76 and thus reducing pilot pressure therein.

(4) Pilot pressure is also reduced in pipe 52 and chamber 119 ofcontroller 53 (FIGURE 11) to balance the same with the pressure incontrol point chamber 118.

(5) Balanced pressure in chambers 118, 119 then raises diaphragms 145,146, 147 and valve core m to neutral position.`

`(6) Additional pressure released from chamber 121 throughy the thenslightly open nozzle 153.

(7) Since pressure is reduced in chamber 121, the higher pressure thenin chamber 122, along with spring D, raises valve seat v further awayfrom needle valve w, permitting additional air to escape therethroughfrom chambers 122, 120 tothe atmosphere. r

(8) Signal pressure is reduced in chambers 120, 122, pipe 55 and chamber185. i

`(9) Spring 180 of actuator 54 raises diaphragms 182, 187, spacer block190 and plates 192, 193.

(10) Valve 194 raises to establish communication between passageway 197and vent chamber 186', while at least partially restrictingcommunication between passageways 196, 197, so that a balanced steadystate condition exists between the forces applied by spring 180 and bypiston 57 and the pressure within chamber 185, thus maintaining anequalizing pressure in conduit 200 and chamber 201.

It is apparent that, upon any tendency for the tension to decrease inthe strand S, sensing roller 36 moves rearwardly or from right to leftin FIGURES 1, 2, Stand 6 as the deflection of cantilever 40 is reduced,thus causing pilot valve 51 to move further inwardly or from right toleft in FIGURE 6 relative to the core 94. This will have substantiallythe same eiect on the fluid pressure circuit as ythat which occurredwhen the cantilever 40 returned from an excessively deilected positionto an optimum position. However, since less than the desired amount ofdeilection then exists in the cantilever 40, the pilot pressure incontroller chamber 119 will then be less than the control point pressurein chamber 118, and this will result in a reduction in the signalpressure in chambers 120, 122 of controller 53, pipe 55 and chamber 185of control unit 183.

As the pressure in chamber V185 is further reduced, spring 180vcausessignal pilot valve 194 to move further upwardly, thus reducing orcompletely stopping the flow of air from pipe 102 into pipe 200 andpermitting air to be exhausted from chamber 201 through pipe 200 intoexhaust chamber 186, and thus through the passageways B, the chamber 175and exhaust port 177 until the forces return to a state of equilibriumsuch that the valve 194 occupies an optimum position permitting the sameamount of air to enter pipe 200 as may leave the same through Vexhaustchamber 186. Of course, when the pressure in chamber 185 was reduced inthe manner last described, it is .apparent that the force of the mainline pressure in chamber 173 and the force of spring 180 on piston 57then exceeded the force applied by the pressure in chamber 201 so thatpiston 57, plunger 60 and movable pins 32, 33 were moved downwardly andincreased the 'tortuosity of and tension in `strand S suiciently to 14return the sensing roller 36 and the free end of cantilever 40 totheoptimum position.

It is apparent that all of these various pressure changes throughout thesystem act very quickly so that substantially simultaneously with anychange in position of the sensing roller 36, a change is etlected in theposition of the movable pins 32, 33 to correspondingly vary thetortuosity of strand S and the tension thus induced there- It should benoted that, when the opposing forces acting upon the diaphragmsV a and83 (FIGURE 7) by the pressures in chambers 70 and 68 of motiontransmitter 44 are in equilibrium, the relationship of the needle valvec and ball valve d to the valve seat 84 and the passageway e is suchthat the exhaust of air through valve seat 84 from chamber 70 is equalto the inward flow of air from supply chamber 71 into chamber 70. Thisis also true with respect to the diaphragms 136, 145, 146, 147, r, s ofFIGURE l0 and the diaphragms 182, 187 of FIGURES 8 and 9.

When the optimum or desired tension induced in the strand S is to beincreased, the screw 131 of the control point setting regulator ofcontroller 53 (FIGURE l0) is adjusted to increase the pressure exertedby spring 134 .against regulator base 135 so that a higher control pointpressure must exist in chamber in order to raise nozzle seat or throttlevalve k out of engagement with the nozzle This increase in control pointpressure in chamber 115 is also reflected in chamber 118 of thethrottling unit of controller 53.

With an increase in control point pressure in chamber 118, the pressuretherein becomes greater than it is in chamber 119 with the result thatdiaphragms 145-147 move upwardly along with valve core m. This releasespressure from chamber 121, permitting valve seat b to move upwardly andthus exhaust air from chambers 120, 122. In so doing, air -is exhaustedfrom chamber 18S in the control unit 183 of actuator 54 (FIGURES 8 and9); It is apparent from the foregoing description of the operation ofactuator 54 that this reduction in pressure in chamber causes a`reduction in pressure in chamber201 below piston 57 so that spring 180and the main line pressure in chamber `173 move piston 57, plunger 60and pins 32, 33 downwardly to increase the tortuosity and tension in thestrand S and cause the sensing roller 36 to occupy .an optimum positionin which greater deflection is imposed upon the cantilever 40 then wasthe case before the control point pressure was increased.

In so doing, pilot valve 51 will have moved from left to right in FIGURE6, which, as heretofore stated, increases the pilot pressure in chambers67, 70 of transmitter 44, pipe 52 and chamber 119 of controller 53. Whenthe pressure in chambers 118, 119 is equalized, rurther increase insignal pressure in chambers 120, 122 1s stopped and the entire fluidpressure circuit then operates in the same manner as that heretoforedescribed with the exception that the tension induced in the strand Sremains greater than it was in the first-described example.

In a third example, when the optimum tension in the strand S is to bedecreased, control point pressure iS reduced by turning screw 131 of thecontrol point regulator 110 of controller 53 so as to decrease thepressure exerted by spring 134 againstrregulator base 135, thusdecreasing the control point pressure in chambers 115, 118. Since thecontrol point pressure in chamber 118 is then lessthan the pilotpressure in chamber 119, it follows from'the foregoing description, thatsignal pressure in chambers 120, 122 of controller 53, in pipe 55 and inchamber 185 of the control unit 183 of actuator 54 is increased, causingdiaphragms 182, l185 to move downwardly (FIGURES 8 and 9) and permittingadditional pressure to enter chamber 201 in the lower end ot cylinder56.

Admission of additional pressure in chamber 201 of cylinder 56 raisesmovable pins 32, 33 to reduce the tortuosity of and tension in strand S.Thus, the deflection of cantilever 40 is decreased as the pull of thestrand S against sensing roller 36 decreases and pilot valve 51 movesfrom right to left in FIGURE 6 relative to the core 94 within bellows92, 93.

From the foregoing description, it is apparent that inward movement ofpilot valve 51 relative to core 94 reduces the pilot pressure inchambers 67, 70 of motion transmitter 44, reduces the pressure in pipe52, and reduces the pressure in chamber 119 of controller 53 to where itagain equals the control point pressure in chamber 118 to maintain ahigher pressure in chambers 120, 122, pipe 55 and chamber 185 (FIGURES 8and 9) than was maintained in these chambers in the first example setforth herein.

It is thus seen that, with very little movement of the sensing roller 36from right to left in FIGURES 5 and 6, such as to increase the length ofthe loop formed in the strand S passing thereabout, pilot pressuretransmitted from motion transmitter 44 to controller 53 is decreasedrelative to control point pressure, causing a corresponding decrease insignal pressure transmitted from controller to chamber 185 of controlunit 183 of actuator 54, thus decreasing the pressure in chamber 201below piston 57 (FIGURE 8) and thereby increasing the intermeshingrelationship of the pins 32, 33 with respect to the pins 26-28 andincreasing the tortuosity of and tension in strand S.

It is seen further that, with the slightest movement of the sensingroller 36 from left to right in FIGURES 5 and 6, such as to reduce thesize of the loop formed in the strand S passing thereby, pilot pressuretransmitted from motion transmitter 44 to chamber 119 of controller 53is increased, to cause a corresponding increase in signal pressure inchambers 120, 122 of controller 53, pipe 55 and chamber 185 of actuatorcontrol unit 183. This increases the pressure in chamber 201 belowpiston 57 and actuator 54 and reduces the intermeshing relationshipbetween pins 32, 33 and pins 26-28, thus reducing the tortuosity of andtension in strand S to return the sensing roller 36 to its originaloptimum position.

It is apparent that, although the present embodiment of the presentinvention is particularly adapted for pneumatic operation, the motiontransmitter, controller and actuator may be of types operated byhydraulic pressure, without departing from the spirit of the invention.

Second Embodment of Sensing Device The cantilever type of yieldablemeans for applying pressure to the sensing roller in opposition to thepull of the strand or other pliable material thereagainst is desirablefrom the standpoint of simplicity, ease of manufacture and installation,and the dimensions of the cantilever type of yieldable supporting meansfor sensing roller 36 may be easily calculated in order that its rate ofdeflection is directly proportional to the load or pressure appliedthereto by the pull of the strand or other moving pliable materialagainst the sensing roller. For example, one cantilever corresponding tothe cantilever 40 was used in which deflection would start upon 5 poundspressure being applied to the free end portion thereof, and said freeend portion was deflected .078 inch upon 35 pounds pressure beingapplied thereto. Since the rate of deflection of the free end of thecantilever 40 was constant at least from zero deflection to .078 inchdellection, it follows that the free end of the cantilever was deflected.0026 inch with each additional pound of pressure applied thereto above5 pounds.

Since there are instances in which the amount of tension induced in amoving strand or web of pliable material may be less than 5 pounds orsubstantially greater than 35 pounds, and might even be as much as 2,000to 3,000 pounds, a second embodiment of means for applying yieldablepresusre to the sensing roller, in opposition to the pull of the strandor web of pliable material, isshown in FIGURE 13 wherein those partswhich are identical to or substantially the same as like parts shown inFIGURES 1 through 5 shall bear the same reference characters, with theprime notation added, in order to avoid repetitive description.

Referring to FIGURE 13, it will be observed that the shaft 37', on whichsensing roller 36 is journaled, is fixed in a bifurcated block 230 whichmay be formed integral with a plunger 231, but is preferably threadedontothe free end of plunger 231 and locked in adjusted position by a nut232. Follower 42 bears against bifurcated block 230. Plunger 231slidably penetrates one end of an enclosure 233, shown in the form of acylinder, and has a spring seat or piston 234 fixed on its inner end.The end of cylinder 233 opposite from that end through which plunger 231extends is closed by an adjustment screw 235 threaded into cylinder 233.

The cylinder 233 is suitably secured to a bracket 236 which is suitablysecured to the frame 30. A coil spring, in the form of a compressionspring 240, is loosely positioned within cylinder 233, one end of whichbears against piston 234 and the other end of which bears against screw235 of cylinder 233. It is apparent that the size and type of the spring240 may be varied, as desired, so that the pressure exerted by thespring 240 against the sensing roller 36 may be predetermined to applyany desired amount of tension to the moving pliable element or strand S.Of course, the size of the spring may be readily calculated in order toobtain a given rate of deflection in accordance with the loads to beapplied to the spring when certain variations in the tension ofdifferent strands or other pliable materials S may be desired. Also, thepressure of spring 240 against piston 234 may be adjusted by adjustingscrew 235.

It is apparent that the movable pins 32, 33 and/or the xed pins 26-28 ofthe friction applying device 22 may be rotatably mounted, as may bedesirable in tensioning plastic film materials or other materials' whichmight be susceptible to damage due to the heat produced by frictionalcontact with a fixed pin or roll. Further, in the instance of any of thepins 26-28, 32, 33 being rotatably mounted, means may be provided forapplying frictional resistance to rotation of such pins to providefurther latitude in the selection of tensions to be applied to thematerial S, without departing from the spirit of the invention. Althoughthe elements for applying tortuosity to the moving strand S are shown inthe form of relatively small anged pins, it is apparent that theprinciples of the present invention are also applicable wherein elongaterolls or shafts are used in place of the pins 26-28, 32, 33 so that theapparatus is readily adapted for applying predetermined uniform tensionto moving web materials. In the latter instance, it may be desirable tosupport the pins 26-28 at each end thereof and to utilize two actuators,such as actuator 54, for supporting opposite ends of the movable pins32. 33.

In instances in which relatively light tension is to be applied to themoving strand S, it is apparent that the two pins 26, 23 may be omitted,or a single one of the pins 32 or 33 may be used in combination with acorresponding pair of the pins 26-28. Further, if the tortuosity of andtension in the strand or other pliable material is to be increasedbeyond the capabilities of the three pins 26-28 and the two movable pins32, 33 to do so, it is apparent that the number of fixed and movablepins may be increased without departing from the spirit of theinvention.

In the drawings and specification there have been set forth preferredembodiments of the invention and, although specific terms are employed,they are used in a generic and descriptive sense only and not forpurposes of ing substantially opposite sides of the material in asuccession of spaced points along its .path of travel and causing thematerial to move in a tortuous path, huid-pressureoperated meansincluding a rst bleed-off valve operatively connected to said engagingmeans for varying the tortuosity of the material to vary proportionallythe frictional resistance applied to the material, a movable sensingelement engaging and forming a loop in said material after it passessaid device, means for applying a predetermined control fluid pressureto said iiuid-pressure-operated means such as to cause said engagingmeans to effect such tortuosity in the material that the frictionalresistance so applied to the material induces an optimum tensiontherein, and means including a second bleed-off valve responsive tomovement of said sensing element relative to an optimum position atwhich said optimum tension exists in the material for correspondinglyvarying the extent of bleed-olf of pressure by said rst bleed-off valveand to vary the pressure in said iluid-pressure-operated means withrespect to said control iiuid pressure.

2. In a structure according to claim l; means for applying yieldablepressure to said sensing element in a direction tending to increase thesize of the loop formed in said material, said last-named meanscomprising a bendable cantilever fixed at one end thereof in relation tosaid device, and said sensing element being carried by said cantileverat a point spaced from said one end thereof.

3. In a structure according to claim l; means for applying yieldablepressure to said sensing element in la direction tending to increase thesize of the loop in said material, and said last-named means comprisinga coil spring operatively connected to and exerting pressure againstsaid sensing element.

4. In4 a structure according to claim 3; means for adjusting said springto vary the pressure exerted against said sensing element.

5. Apparatus for maintaining tension in a moving pliable material ofindelinite length comprising at least one first pin, at least two spacedsecond pins straddling said first pin, said first and second pins beingengageable with Vopposite sides of the material to induce tortuosity inand apply friction to the material, fluid-pressure-operated meansincluding a first bleed-off valve for varying the relative positions ofsaid first and second pins independently of the tension of the materialmoving between said second pins and serving to vary the tortuosity inand the friction applied to the material, a yieldable sensing element inspaced relation to said first and second pins and engageable by thematerial after it passes said first and second pins, means connectingsaid iluid-preSsure-operated means to a source of fluid pressure, saidsensing element being movable in response to variation in the tension inthe material after it passes said rst and second pins, and meansincluding a second bleed-off valve interposed in said connecting meansand being responsive to movement of said sensing element to vary theextent of bleed-off of pressure by said first bleed-olf valve and tovary the pressure in said iluid-pressure-operated means to cause saidfirstnamed means to vary the relative positions of said first and secondpins whereby the tortuosity and friction induced in the material isvaried in accordance with variations in the tension of the -materialafter it passes the first and second pins to maintain uniform tension inthe material.

6. In an lapparatus for tensioning a moving pliable material of indenitelength comprising a device for applying tension to the material, saiddevice including at least one means engaging the moving material, andmovable means operatively associated with said engaging means forvarying the tension applied to the material in accordance with theposition of said movable means; lthe combination ofuid-pressure-operated means for imparting movement to said movable meansand including frst and second relatively movable parts, a yieldablesensing element engaging the material under yieldable pressure after itpasses said engaging means, pressure converting means connected to lasource of fluid pressure land including means responsive to movement ofsaid sensing element for converting the pressure from saidsource to ameasured pilot pressure varying in direct linear relation with themovement of said sensing element, means producing a predeterminedcontrol point pressure, means fol comparing said measured pilot pressurewith said control point pressure to produce a varying signal pressurecorresponding to the comparison of said measured pilot pressure withsaid control point pressure, communicative means connecting saidiiuid-pressure-operated means to a source of tluid pressure, and meansin said communicative means and being responsive to said varying signalpressure for varying the amount of fluid pressure eifective in saidrfluid-pressure-operated means to cause relative movement |between saidfirst and second par-ts to thereby vary the position of said movablemeans such aS to vary the tension applied to the material in response tovariations in the position of said sensing element to maintainpredetermined uniform tension in the material.

7. Apparatus for processing a moving pliable material of indefinitelength comprising a device under control of the material, ysaid devicecomprising fluid-pressure-operated means and including first and secondrelatively movable parts, a yieldable `sensing element spaced from saidrelatively movable parts and engaging the material under yieldablepressure and being movable by engagement with the material, pressureconverting means connected to a -source of fluid pressure and includingmeans movable with said sensing element for converting the pressure fromsaid source to a measured pilot pressure varying in direct linearrelation with the movement of said sensing element, means producing apredetermined control point pressure, means for comparing said measuredpilot pressure with said control point pressure to produce a varyingsignal pressure corresponding to the comparison of said measuredpilot-pressure with said control point pressure, communicative meansconnecting said fluid-pressure-operated means to said source of fluidpressure, and means responsive to said -varying signal pressure forvarying the amount of fluid pressure effective in saidfluid-pressure-operated means to cause relative movement between saidfirst and second parts such as t0 vary the position thereof in response-to variations in the position of said sensing element.

8. Apparatus for tensioning a moving pliable material comprising adevice for applying frictional resistance to the movement of saidmaterial therethrough, said device including means engaging andimparting la tortuous configuration to the material and thereby applyingfrictional resistance -to the movement of said material,fluid-pressure-operated means including a first bleed-off valveoperatively connected to said engaging means, movable sensing meansengageable Iby the material after it passes said device, means includinga 4second bleed-olf valve operatively interconnecting `said first'bleed-olf valve and said sensing means and varying the extent ofbleed-off pressure by said iirst bleed-off valve, said sensing meansbeing responsive to the tension in the pliable material after passingsaid device yfor controlling said second bleed-ofic valve whereby thepressure in said lfluid-pressure-operated means is varied by said tfirstbleed-off valve in accordance with variations in the position of saidsensing means caused `by variations in the tension of the material, andsaid iluid-pressure-operated means being operable to vary the tortuosityof the material and the consequent frictional resistance to movementthereof in accordance with the pressure admitted to saidhuid-pressure-operated means to maintain a uniform tension in thepliable material at all times.

9. Apparatus for applying and maintaining uniform tensionin a movingpliable material comprising a device for applying frictional resistanceto the movement of said material therethrough, said device including aplurality of pins engaging substantially opposite sides of the materialand causing the material to move in a tortuous path,fiuid-pressure-operated means including a first bleedoff valveoperatively connected to said pins for varying the tortuosity of thematerial and the angle of contact of the material with said pins to varyproportionally the frictional resistance applied to the material, amovable sensing element engaging and forming a loop in said materialafter it passes said device, means for applying a predeterminedyieldable force to said sensing means in opposition to the pull of thematerial thereagainst, means for applying a predetermined control pointpressure to said iuid-pressure-operated means such as to cause said pinsto effect such tortuosity in the material that the frictional resistanceso applied to the material induces an optimum tension therein, and meansincluding a second zbleed-off valve responsive to movement of saidsensing element relative to an optimum position at which said optimumtension exists in the material for correspondingly varying the extent ofbleed-olf of pressure by said first bleed-off valve and to vary thepressure in said fluid operated means with respect to said control pointpressure.

10. Apparatus for tensioning a moving pliable material of indefinitelength comprising first and second spaced means engaging opposite sidesof the material and thus applying friction to the material, afluidpressure-operated actuator including a piston and a cylinder, meansconnecting said first engaging means in fixed relation to said piston,means applying a yieldable force against one side of said piston, asensing element operatively connected to said actuator and engageable bythe material after it passes said first and second engaging means, saidsensing element being movable in response to variations in the tensionin the material after it passes said first and second engaging means,means applying a predetermined opposing pressure against said piston ina direction opposite from said yieldable -force when said sensingelement occupies a predetermined optimum position and Said material isunder a consequent predetermined tension, and means responsive tomovement of said sensing element in either direction relative to saidoptimum position for varying the opposing pressure applied to saidpiston relative to said predetermined opposing pressure to therebychange the position of said first engaging means relative to the secondengaging means whereby the friction induced in the material by the firstand second engaging means is varied in accordance with Variations in thetension of the material after it passes the first and second engagingmeans to maintain uniform tension in the material.

ll. Apparatus for tensioning a moving pliable material of indefinitelength comprising a device for applying frictional resistance to themovement of said material therethrough, said device including first andsecond pin means engaging opposite sides of the material and imparting atort-nous configuration thereto, a fluidpressure-operated actuatorincluding a fixed part and a movable part, means connecting said firstpin means in fixed relation to said movable part, means applying apredetermined fiuid pressure to said movable part in one direction andthereby tending to move said first pin means in said one directionrelative to said second pin means, a movable sensing element operativelyconnected to said actuator, said sensing element being adapted to engageand form a loop in said material after it passes Sad device, means forapplying a predetermined, yieldable lforce to said sensing means inopposition to the pull of the material thereagainst whereby saidmaterial passes said sensing element under tension after it passes saiddevice, means applying a predetermined opposing fluid pressure force tosaid movable part of said actuator in the opposite direction from thatin which said firstmentioned predetermined fluid pressure is applied,and means responsive to variations in the position of said sensingelement due to changes in the tension in said material to vary theopposing iiuid pressure force applied to said movable part in directlinear relationship to the movement of said sensing element and tothereby vary the position of said first pin means relative to the secondpin means whereby the tortuosity and friction induced in the material isvaried in accordance with variations in the tension of the materialleaving the first and second pin means to maintain uniform tension inthe material.

12. Apparatus for tensioning a moving pliable material of indefinitelength comprising an actuator connected to a source of uid pressure, asensing element engaging and being movable in response to variations inthe tension of said material, pressure converting means connected tosaid source and including means movable with said sensing element forconverting said fiuid pressure to a reduced pilot pressure varying indirect linear relation with the movement of said sensing element, `acontroller including first, second and third pressure chambers, manuallyadjustable means for maintaining a predetermined control point pressurein said second chamber, communicative means for transmitting pilotpressure from said converting means to said first chamber, meansresponsive to variations in the pilot pressure in said first chamberrelative to the control point pressure `for producing a concurrentlyvarying signal pressure in said third chamber, said actuator comprisinga fixed part and a movable part, first and second relatively staggeredpin means engageable with opposite sides of and inducing tortuosity inthe material in advance of said sensing element, means operativelyconnecting said first pin means to said movable part so said first pinmeans may move inwardly and outwardly relative to said second pin means,means applying a continuous yieldable force against one side of saidmovable part, valve means interposed between said pressure source andsaid actuator for directing fiuid pressure against said other side ofsaid movable part, and means responsive to variations in said signalpressure for controlling said valve means to vary correspondingly thepressure against said other side of said movable part whereby theposition of said first pin means is varied to vary the tortuosity of andfriction applied to said material in response to variations in theposition of said sensing element to maintain uniform tension in thematerial.

13. Apparatus for tensioning a moving pliable material of indefinitelength comprising a device for applying frictional resistance to themovement of the material therethrough, said device including first andsecond relatively movable friction applying means engageable withopposite sides of the material, fluid-pressure-operated means forimparting relative movement to said rst and second friction applyingmeans including first and second relatively movable parts, a yieldablesensing element engaging the material under yieldable pressure andforming a loop therein after it passes said friction applying means,pressure converting means connected to a source of substantiallyconstant iiuid pressure and including means movable with said sensingelement for converting said substantially constant pressure to ameasured pilot pressure varying in direct linear relation with themovement of said sensing element, means producing a predeterminedcontrol point pressure, means for comparing said measured pilot pressurewith said control point pressure to produce a varying signal pressurecorresponding to the comparison of said measured pilot pressure withsaid con- -trol point pressure, communicative means connecting saidfiuid-pressure-operated means to said source of fluid pressure, andmeans in said communicative means and being responsive to said varyingsignal pressure for varying the amount of fluid pressure effective Vinsaid fluid-pressureoperated means to cause relative movement betweensaid first and second parts and said first and second friction applyingmeans such as to vary the frictional resistance applied to the materialin response to variations in the position of said sensing element tomaintain predetermined uniform tension in the material.

14. Apparatus for tensioning a moving pliable material of indefinitelength comprising a device for applying frictional resistance to themovement of the material therethrough, said device including first andsecond relatively movable and relatively staggered friction applyingpins engageable with opposite sides of the material and causing the sameto move in a tortuous path, fluid-pressureoperated means for impartingrelative movement to said first and second friction applying pinsincluding first and second relatively movable parts, a yieldable sensingelement engaging the material under yieldable pressure and forming aloop therein after it passes said friction applying means, pressureconverting means connected to a source of substantially constant fluidpressure and including means movable [with said sensing element forconverting said substantially constant pressure to a measured pilotpressure varying in direct linear relation with the movement of saidsensing element, means producing a predetermined control point pressure,means for cornparing said measured pilot pressure with said controlpoint pressure to produce a varying signal pressure corresponding to thecomparison of said measured pilot pressure with said control pointpressure, communicative means connecting said fiuid-pressure-operatedmeans to said source of fluid pressure, and means in said communicativemeans and being responsive to said varying signal ressure for varyingthe amount of iiiuid pressure effective in said fluid-pressure-operatedmeans to cause relative movement between said first and second parts andsaid first and second friction applying pins such as to vary thefrictional resistance applied to the material in re- Cil sponse tovariations in the position of said sensing element to maintainpredetermined Vuniform tension in the material.

l5. Apparatus for tensioning a moving pliable material of indefinitelength comprising an actuator connected to a source of fluid pressure, asensing element engaging and being movable in response to variations inthe tension of said material, pressure converting means connected tosaid source and including means movable with said sens-A ing element forconverting said fluid pressure to a reduced pilot pressure varying indirect linear relation with the movement of said sensing element, acontroller including first, second and third pressure chambers, manuallyadjustable means for maintaining a predetermined control point pressurein said second chamber, communicative means for transmitting pilotpressure from aid converting means to said first chamber, meansresponsive to variations in the pilot pressure in said first chamberrelative to the control point pressure for producing a concurrentlyvarying signal pressure in said third chamber, said actuator comprisinga fixed part and a movable part, first and second friction applyingmeans engageable with opposite sides of any applying frictionalresistance to movement of the material in advance of said sensingelement, -means operatively connecting said first friction applyingmeans to said movable part so said latter means may move inwardly andoutwardly relative to said second friction applying means, meansapplying a continuous yieldable force against one side of said movablepart, valve means interposed between said pressure source and saidactuator and being arranged to direct fluid pressure against said otherside of said movable part, and means responsive to variations in saidsignal pressure for controlling said valve means to vary correspondinglythe pressure against said other side of said movable part whereby theposition of said first friction applying means is varied to vary thetortuosity of and friction applied to said material in response tovariations in the position of said sensing element to maintain uniformtension in the material.

16. Apparatus for tensioning a moving pliable material of indefinitelength comprising a motion transmitter, a controller and an actuatorconnected to a source of substantially constant fluid pressure, asensing element engaging and being movable in response to variations inthe tension of said material, means in said transmitter movable withsaid sensing element for converting said constant fluid pressure to apilot pressure varying in direct linear relation With the movement ofsaid sensing element, said controller including a first chamber, asecond chamber and a third chamber, means for maintaining apredetermined control point pressure in said second chamber,communicative means for transmitting pilot pressure from saidtransmitter to said first chamber, means responsive to variations in thepressure in said first chamber relative to the lcontrol-point pressurefor producing a concurrently varying signal pressure in said thirdchamber, sai-d actuator comprising a fixed part and a movable part, saidmovable part having a lesser effective surface a-rea on one side thereofthan that on the other side thereof, first and second friction applyingmeans engageable with opposite sides of the material in advance of saidsensing element, means operatively connecting said first frictionapplying means to said movable part so said first friction applyingmeans may move inwardly and outwardly relative to said second frictionapplying means, said actuator being so connected tothe pressure sourcethat continuous yieldable fluid pressure is applied against said oneside of said movable part, valve means connecting said source to saidactuator for directing fluid pressure against said other side of saidmovable part, and means responsive to variations in said signal pressurefor controlling said Valve means to vary proportionally the pressureagainst said other side of said'movable part whereby the position o fsaid first friction applying means is varied to vary the frictionapplied to said material in response to variations in the position ofsaid sensing element and thereby to maintain uniform tension in thematerial.

l7. Apparatus for tensioning a moving pliable material of indefinitelength comprising a motion transmitter, a controller and an actuatorconnected to a source of substant-ially constant fluid pressure, asensing element engaging and 4being movable in response to vari-ationsin the tension of said material, means in said transmitter movable withsaid sensing element for converting said fluid pressure to a reducedpilot pressure varying in direct linear relation with the movement ofsaid sensing element, said controller including a pilot pressurechamber, a control point pressure chamber and a signal pressure chamber,means for maintaining a predetermined control point pressure in saidcontrol point pressure cham-ber, communicative means for transmittingpilot pressure from said transmitter to said pilot pressure chamber,means responsive to variations in the pressure in said pilot pressurechamber relative to the .control point pressure for producing aconcurrently varying signal pressure in said signal pressure chamber,said actuator comprising a fixed part an-d a movable part, said movablepart having a lesser effective surface area on one side thereof thanthat on the other side thereof, first and second relatively staggeredpin means engageable with opposite sides of and inducing tortuosity inthe material in advance of said sensing'element, means operativelyconnecting said first pin means to said movable part so said first pinmeans may move inwardly and outwardly relative to said second pin means,said actuator being so connected to the pressure source that continuoussub- 23 stantially uniform pressure is applied against said one side ofsaid movable part, valve means connecting said source to said actuatorfor directing fiuid pressure against said other side of said movablepart, and means responsive to variations in said signal pressure forcontrolling said valve means to vary the pressure against said otherside of said movable part whereby the position of said first pin meansis varied to vary the tortuosity of and `friction applied to saidmaterial in response to variations in the position of said sensingelement to maintain uniform tension in the material.

18. Apparatus for tensioning a moving pliable material of indefinitelength comprising a pneumatic actuator connected to a source of airunder substantially constant pressure, a sensing element engaging andbeing movable in response to variations in the tension of said material,pressure converting means connected to said source and including meansmovable with said sensing element for converting said air under pressureto a pilot air pressure varying in direct linear relation with themovement of said sensing element, a controller including first, secondand third spaced diaphragms defining first, second and third pressurechambers, a valve core carried by an interconnecting said diaphragms,manually adjustable means for maintaining a predetermined control pointair pressure in said second chamber, communicative means fortransmit-ting pilot air pressure from said converting means to saidlirst chamber whereby said diaphragms move in one direction when thepilot pressure is less than the control point pressure and in theopposite direction when the pilot pressure is greater than the controlpoint pressure, means responsive to movement of the valve core with thediaphragms for producing a varying signa'l pressure in said thirdchamber, said actuator comprising first and second relatively movableparts, tirst and second relatively movable means engageable withopposite sides of and applying frictional resistance to the movement ofthe material in advance of said sensing element, means operativelyconnecting said lirst movable means to said irst movable part, meansapplying a continuous yieldable force against one side of one of saidrelatively movable parts, valve means interposed between said pressuresource and said actuator for directing air pressure against the otherside of said one of said movable parts, and means responsive tovariations in said signal pressure for controlling said valve means tovary correspondingly the air pressure against said other side of saidone of said movable parts whereby the relative positions of said tirstand second means are varied to vary the friction applied to saidmaterial in response to Variations in the position of said sensingelement to maintain uniform tension in the material.

19. Apparatus for applying and maintaining uniform tension in a movingpliable material comprising a tensioning device including at least onemeans engaging the moving material and movable means operativelyassociated with said engaging means for applying tension to the materialvarying in accordance with the position of said movable means,uid-pressure-operated means including a first bleed-off valveoperatively connected to said movable means to vary the position thereofrelative to said engaging means to thereby vary the tension applied tothe material, a movable sensing means engaging said material after itpasses said tensioning device, means for applying a predeterminedcontrol pressure to said fluid-pressure-operated means so as to causesaid movable means to effect a predetermined frictional resistance tothe movement of the material and induce an optimum tension therein, andmeans including a second bleedofi-valve responsive to movement of saidsensing means relative -to an optimum position at which said optimumtension exists in the material for correspondingly varying the extent ofbleed-oit of pressure by said first bleedoff valve and to vary thepressure in said huid-pressureoperated means with respect to saidcontrol pressure.

References Cited in the file of this patent UNITED STATES PATENTS2,117,412 Freeman May 17, 1938 2,888,216 Simons et al. May 26, 19592,920,772 Wilhelm et al. Jan. 12, 1960 2,964,259 Peel Dec. 13, 1960UNITED STATES PATENT OFFICE CERTIFICATE OE CORRECTION Patent No.3,072,360 January 8, 1963 Paul L. Cruz It is hereby certified that errorappears in the above numbered patent requiring -correction and that thesaid Letters Patent should read as corrected below.

Column 2, line 6, for "adjusing" read adjusting. -;n column 6, line 66,for "inteposed" read interposed column 7, line 51, forl "atmospehre"read atmosphere column 8, line 2, for "enagement" read engagement line62, before "valves" insert and ;l column 9, 1in-e lO, for "intregal"read integral column lO, line 35, for "intergal" read integral column11, line 73, for "that" read there column 13, line 141,v for "vlave"read valve column 16, line 59, for "pins 32. 33. read pins 32, 33.column 2], line 63, fOr* "any" read and column V23, line 24, for an readand Signed and sealed this 9th day of July 1963,

(SEAL) Attest:

ERNEST W. SWIDEE DAVID L. LADD Attesting Officer V Commissioner ofPatents

1. APPARATUS FOR APPLYING AND MAINTAINING UNIFORM TENSION IN A MOVINGPLIABLE MATERIAL COMPRISING A DEVICE FOR APPLYING FRICTIONAL RESISTANCETO THE MOVEMENT OF SAID MATERIAL THERETHROUGH, SAID DEVICE INCLUDINGMEANS ENGAGING SUBSTANTIALLY OPPOSITE SIDES OF THE MATERIAL IN ASUCCESSION OF SPACED POINTS ALONG ITS PATH OF TRAVEL AND CAUSING THEMATERIAL TO MOVE IN A TORTUOUS PATH, FLUID-PRESSUREOPERATED MEANSINCLUDING A FIRST BLEED-OFF VALVE OPERATIVELY CONNECTED TO SAID ENGAGINGMEANS FOR VARYING THE TORTUOSITY OF THE MATERIAL TO VARY PROPORTIONALLYTHE FRICTIONAL RESISTANCE APPLIED TO THE MATERIAL, A MOVABLE SENSINGELEMENT ENGAGING AND FORMING A LOOP IN SAID MATERIAL AFTER IT PASSESSAID DEVICE, MEANS FOR APPLYING A PREDETERMINED CONTROL FLUID PRESSURETO SAID FLUID-PRESSURE-OPERATED MEANS SUCH AS TO CAUSE SAID ENGAGINGMEANS TO EFFECT SUCH TORTUOSITY IN THE MATERIAL THAT THE FRICTIONALRESISTANCE SO APPLIED TO THE MATERIAL INDUCES AN OPTIMUM TENSIONTHEREIN, AND MEANS INCLUDING A SECOND BLEED-OFF VALVE RESPONSIVE TOMOVEMENT OF SAID SENSING ELEMENT RELATIVE TO AN OPTIMUM POSITION ATWHICH SAID OPTIMUM TENSION EXISTS IN THE MATERIAL FOR CORRESPONDINGLYVARYING THE EXTENT OF BLEED-OFF OF PRESSURE BY SAID FIRST BLEED-OFFVALVE AND TO VARY THE PRESSURE IN SAID FLUID-PRESSURE-OPERATED MEANSWITH RESPECT TO SAID CONTROL FLUID PRESSURE.